Arthur
You might have a hard time finding a Tillotson as they often were made of pot metal and don't last. There are three of them on Ebay now for parts, but I'm not sure which ones or what condition they are. If the carb you have now works, I'd keep it, but if it's not working properly, Frank W. Sells a great carb to use in its place.
Do You own a car built by Durant? 1928 Durant Model 65 4 door
doesn't frank w sell a replcement carb for those years that everyone says is better than the original ever was??? maybe you should consider that small change from original to prevent letdown at poor times